11-25-2009, 05:11 PM
Dynamics brakes typically don't work below... say... 10 mph. Newer units, especially AC units, have dynamics that work to much lower speeds... i think around 3 mph. But Russ is absolutely right, they are for maintaining speed, not for stopping, although when an engineer is trying to stop ASAP without dynamiting the train then he will give a full service reduction on the automatic brake and full dynamic brakes. If the train gets dynamited (goes into emergency) then no dynamic would be used and the independent would get bailed off to prevent run in on the locos.
I don't think it's been mentioned but for those who are wondering, locomotives nowadays typically have 4 brakes on them, Dynamic (reverses the motors for braking), independent (air brakes for the loco only), automatic (air brakes for the loco and train), and the hand brake.
I believe the ropes hanging above the train before underpasses and tunnels were called tell tales and yes, they were there to warn brakemen on the roof top to GET DOWN NOW!
I don't think it's been mentioned but for those who are wondering, locomotives nowadays typically have 4 brakes on them, Dynamic (reverses the motors for braking), independent (air brakes for the loco only), automatic (air brakes for the loco and train), and the hand brake.
I believe the ropes hanging above the train before underpasses and tunnels were called tell tales and yes, they were there to warn brakemen on the roof top to GET DOWN NOW!
-Dave